After a few seconds, if the modloader hasn't yet found the snake code then it will show a message saying that the snake code hasn't been found. This means that the mod won't be applied.
If this happens, you should first make sure you are on the latest version (see here for how to update).
If this issue is still happening then please tell us about it by raising an issue. We will then be able to release an update to correct for whatever change has happened.